WHO announces recommended viral composition for 2025 influenza vaccines

The World Health Organization (WHO) today announced the recommendations for the viral composition of influenza vaccines for the 2025 influenza season in the southern hemisphere. The announcement was made at an information session after a 4-day meeting on the Composition of Influenza Virus Vaccines. The meeting is held twice annually, once for the southern and once for the northern hemisphere. 

WHO organizes these consultations with an advisory group of experts gathered from WHO Collaborating Centres and WHO Essential Regulatory Laboratories to analyze influenza virus surveillance data generated by the WHO Global Influenza Surveillance and Response System (GISRS). The recommendations issued are used by the national vaccine regulatory agencies and pharmaceutical companies to develop, produce, and license influenza vaccines for the following influenza season. 

The periodic update of viruses contained in influenza vaccines is necessary for the vaccines to be effective due to the constant evolving nature of influenza viruses, including those circulating and infecting humans.

The WHO recommends that trivalent vaccines for use in the 2025 southern hemisphere influenza season contain the following: 

Egg-based vaccines 

• an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
• an A/Croatia/10136RV/2023 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

Cell culture-, recombinant protein- or nucleic acid-based vaccines

• an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
• an A/District of Columbia/27/2023 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

The recommendation for the B/Yamagata lineage component of quadrivalent influenza vaccines remains unchanged from previous recommendations:

• a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.